MyBatis01基于配置的CRUD操作

Posted 2020-12-18 elaina

• 创建Maven工程
• 导入依赖

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.3</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.16</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
    </dependencies>

• 创建数据库

CREATE TABLE `user` (
  `id` int NOT NULL,
  `username` varchar(32) DEFAULT NULL,
  `password` varchar(32) DEFAULT NULL,
  PRIMARY KEY (`id`)
)

• 编写实体类

package blog.mybatis.domain;

public class User {

    private Integer id;
    private String username;
    private String password;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username=‘" + username + ‘‘‘ +
                ", password=‘" + password + ‘‘‘ +
                ‘}‘;
    }
}

• 创建数据库配置文件db.properties

driver = com.mysql.cj.jdbc.Driver
url = jdbc:mysql://localhost:3306/mybatis?characterEncoding=utf8&serverTimezone=GMT%2B8
username = root
password = 123456

• 创建MyBatis主配置文件SqlMapConfig.xml

<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">

<!-- mybatis的主配置文件 -->
<configuration>
    <!-- 加载类路径下的属性文件 -->
    <properties resource="db.properties"/>
    <!-- 配置环境 -->
    <environments default="mysql">
        <!-- 配置mysql的环境 -->
        <environment id="mysql">
            <!-- 配置事务类型 -->
            <transactionManager type="JDBC"></transactionManager>
            <!-- 配置数据源（连接池） -->
            <dataSource type="POOLED">
                <!-- 配置连接数据库的4个基本信息 -->
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${username}"/>
                <property name="password" value="${password}"/>
            </dataSource>
        </environment>
    </environments>

    <!-- 指定映射配置文件的位置 -->
    <mappers>
        <package name="blog.mybatis.dao"/>
    </mappers>
</configuration>

• 编写UserDao

package blog.mybatis.dao;

import blog.mybatis.domain.User;

import java.util.List;

/**
 * 用户持久层接口
 */
public interface UserDao {

    /**
     * 查询所有
     * @return
     */
    List<User> findAll();

    /**
     * 添加用户
     */
    void saveUser(User user);

    /**
     * 更新用户
     * @param user
     */
    void updateUser(User user);

    /**
     * 删除用户
     * @param userId
     */
    void deleteUser(Integer userId);

    /**
     * 根据id查询用户信息
     * @param userId
     * @return
     */
    User findById(Integer userId);

    /**
     * 根据名称模糊查询
     * @param username
     * @return
     */
    List<User> findByName(String username);
}

• UserDao映射配置文件UserDao.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="blog.mybatis.dao.UserDao">

    <!-- 查询所有 -->
    <select id="findAll" resultType="blog.mybatis.domain.User">
        select * from user
    </select>

    <!-- 保存用户 -->
    <insert id="saveUser" parameterType="blog.mybatis.domain.User">
        <!-- 配置插入操作后，获取插入数据的id -->
        <selectKey keyProperty="id" keyColumn="id" resultType="int" order="AFTER">
            select last_insert_id()
        </selectKey>
        insert into user(username,password)values(#{username},#{password})
    </insert>

    <!-- 更新用户 -->
    <update id="updateUser" parameterType="blog.mybatis.domain.User">
        update user set username=#{username}, password=#{password} where id=#{id}
    </update>

    <!-- 删除用户 -->
    <delete id="deleteUser" parameterType="Integer">
        delete from user where id = #{uid}
    </delete>

    <!-- 根据id查询用户 -->
    <select id="findById" parameterType="INT" resultType="blog.mybatis.domain.User">
        select * from user where id = #{uid}
    </select>

    <!-- 根据名称模糊查询用户信息 -->
    <select id="findByName" parameterType="string" resultType="blog.mybatis.domain.User">
        select * from user where username like #{name}
    </select>
</mapper>

• 测试

package blog.mybatis.Test;

import blog.mybatis.dao.UserDao;
import blog.mybatis.domain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.InputStream;
import java.util.List;

public class Test {

    private InputStream in;
    private SqlSession sqlSession;
    private UserDao userDao;

    @org.junit.Before//在Test执行之前执行
    public void init() throws Exception {
        //1.读取配置文件，生成字节输入流
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.获取SqlSessionFactory
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        //3.获取SqlSession对象
        sqlSession = factory.openSession();
        //4.获取dao的代理对象
        userDao = sqlSession.getMapper(UserDao.class);
    }

    @org.junit.After//在Test执行之后执行
    public void destroy() throws Exception {
        //提交事务
        sqlSession.commit();

        //6.释放资源
        sqlSession.close();
        in.close();
    }

    /**
     * 测试查询所有
     * @throws Exception
     */
    @org.junit.Test
    public void testFindAll() {
        //5.执行查询所有方法
        List<User> users = userDao.findAll();
        for (User user : users) {
            System.out.println(user);
        }
    }

    /**
     * 测试保存操作
     */
    @org.junit.Test
    public void testSave() {
        User user = new User();
        user.setUsername("Tom");
        System.out.println("保存操作之前:" + user);

        //5.执行保存方法
        userDao.saveUser(user);

        System.out.println("保存操作之后:" + user);
    }

    /**
     * 测试更新操作
     */
    @org.junit.Test
    public void testUpdate() {
        User user = new User();
        user.setId(3);
        user.setUsername("Jerry");

        //5.执行更新方法
        userDao.updateUser(user);
    }

    /**
     * 测试删除操作
     */
    @org.junit.Test
    public void testDelete() {
        //5.执行删除方法
        userDao.deleteUser(3);
    }

    /**
     * 测试根据id查询操作
     */
    @org.junit.Test
    public void testFindById() {
        //5.执行根据id查询用户方法
        User user = userDao.findById(1);
        System.out.println(user);
    }

    /**
     * 测试模糊查询操作
     */
    @org.junit.Test
    public void testFindByName() {
        //5.执行模糊查询方法
        List<User> users = userDao.findByName("%M%");
        for (User user : users) {
            System.out.println(user);
        }
    }
}